dft.m

新版Matlab 7辅助信号处理技术与应用

function [xk]=dft(xn,N)
%this program computes Discrete Fourier Transform
%its format is
%xk= IDFT(xn,N)
%N is length of IDFT
%xn is IDFT coeff. Array over 0<=k<=N-1
%xk is N-point sequence over 0<=k<=N-1

n=[0:1:N-1]; % n的行向量
k=[0:1:N-1]; %k的行向量
WN=exp(-j*2*pi/N); %旋转因子
nk=n'*k; %产生一个台nk值的N乘N维矩阵
WNnk=WN.^nk; % DFT矩阵
xk=xn*WNnk; %DFT系数的行